Ideal Logic+ Combi C Fault codes & diagnostics

10 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.

Combi Natural Gas 2016-present
GC Numbers 47-349-1547-349-1647-349-1747-349-9347-349-9447-349-95
Download the Ideal Logic+ Combi C manual The official installation & service manual (PDF) — the exact document these fault codes were verified against. PDF

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Severity at a glance

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10 High
Versions & GC numbers

Which version do you have?

The GC number on your boiler's data badge identifies the exact appliance and production years, as recorded in the UK Product Characteristics Database.

GC number Appliance (register name) Produced
47-349-15 LOGIC + COMBI C24 2016–present
47-349-16 LOGIC + COMBI C30 2016–present
47-349-17 LOGIC + COMBI C35 2016–present
47-349-93 LOGIC COMBI2 C24 2022–present
47-349-94 LOGIC COMBI2 C30 2022–present
47-349-95 LOGIC COMBI2 C35 2022–present
Just want the most common Ideal Logic+ Combi C faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 10 documented codes

Tap any card for details

Ignition Lockout 1/2

Your boiler has tried to light several times but failed, so it has locked itself for safety to prevent gas from building up.

High DIY-safe £100-280

What to check first

  1. Check that your gas emergency control valve (usually located by the gas meter) is open.
  2. Check if other gas appliances, like a hob, are working to confirm your gas supply is active.
  3. Press and hold the 'Restart' button for two seconds to allow the boiler to try lighting again.

Parts commonly replaced

  • Ignition Electrode
  • Gas Valve
  • Spark Generator
  • Flame Sensing Probe

Related codes

Full explanation for Ignition Lockout 1/2
Ignition Lockout 2/2

Your boiler has failed to light three times in a row and has locked itself for safety.

High DIY-safe £100-350

What to check first

  1. Check that your gas pre-payment meter (if you have one) has credit.
  2. Verify that other gas appliances, like a cooker, are working to ensure a gas supply.
  3. Press the 'Restart' button on the front panel to attempt a reset.

Parts commonly replaced

  • Ignition Electrode
  • Gas Valve
  • PCB
  • Spark Lead

Related codes

Full explanation for Ignition Lockout 2/2
Overheat Lockout 1/4

Your boiler has shut down because the internal water pressure has dropped too low to operate safely, causing it to get too hot.

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (usually two blue handles or a metal braided hose underneath the boiler).
  2. Slowly open the valves until the needle on the pressure gauge reaches 1.5 bar.
  3. Close the valves tightly and press the 'Restart' button on the boiler control panel.

Parts commonly replaced

  • None (Pressure top-up)
  • Filling loop valve
  • Expansion vessel

Related codes

Full explanation for Overheat Lockout 1/4
Overheat Lockout 2/4

Your boiler has shut down because the water inside it has become too hot, usually due to low water pressure or trapped air.

High DIY-safe £80-250

What to check first

  1. Check the pressure gauge and top up the system to 1.5 bar using the filling loop
  2. Bleed your radiators with a radiator key to remove trapped air
  3. Press the 'Reset' button on the front of the boiler control panel

Parts commonly replaced

  • Overheat Thermostat
  • Circulating Pump
  • Primary Heat Exchanger

Related codes

Full explanation for Overheat Lockout 2/4
Overheat Lockout 3/4

Your boiler has switched itself off because it has become too hot internally, usually because water isn't flowing through the system properly.

High DIY-safe £80-250

What to check first

  1. Check that all radiator valves (TRVs) are turned to the highest setting.
  2. Ensure the blue-handled isolation valves underneath the boiler are in the 'open' position (pointing towards the boiler).
  3. Press the 'Restart' button on the front control panel.
  4. Check the boiler pressure gauge is between 1.0 and 1.5 bar.

Parts commonly replaced

  • Circulating Pump
  • Overheat Thermostat
  • Main Heat Exchanger (if scaled up)

Related codes

Full explanation for Overheat Lockout 3/4
Overheat Lockout 4/4

Your boiler has become too hot and has shut itself down as a safety precaution to prevent damage.

High DIY-safe £120-£350

What to check first

  1. Check that all radiator valves are fully open to allow water to flow.
  2. Ensure there are no blockages or trapped air by bleeding your radiators.
  3. Press the 'Restart' button on the boiler control panel once the system has cooled down.

Parts commonly replaced

  • Overheat Thermostat
  • Central Heating Pump
  • Heat Exchanger (Flushing/Cleaning)

Related codes

Full explanation for Overheat Lockout 4/4
PCB Fault / Contact Installer

Your boiler's internal computer has either lost its memory or suffered a hardware failure, meaning the system cannot safely operate or talk to the components.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB
  • Configuration Chip

Related codes

Full explanation for PCB Fault / Contact Installer
Water Pressure 1/3

Your boiler has detected that the water pressure is too low for the system to operate safely and effectively.

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (braided silver hose) underneath your boiler.
  2. Slowly open the blue or black taps until you hear water moving and see the pressure gauge rise.
  3. Close the taps tightly when the gauge reaches 1.0 - 1.5 bar.

Parts commonly replaced

  • Filling loop
  • Expansion vessel
  • Pressure relief valve

Related codes

Full explanation for Water Pressure 1/3
Water Pressure 2/3

Your boiler’s water pressure has dropped too low to operate, which is usually caused by a small leak or after bleeding your radiators.

High DIY-safe £0-120

What to check first

  1. Locate the filling loop handles (usually two blue or black taps) underneath the boiler.
  2. Slowly turn both handles 90 degrees until you hear water flowing and the pressure gauge rises.
  3. Close both taps tightly once the pressure reaches 1.5 bar on the display.

Parts commonly replaced

  • Filling loop
  • Pressure sensor
  • Expansion vessel

Related codes

Full explanation for Water Pressure 2/3
Water Pressure 3/3

Your boiler has detected that the water pressure is too low to operate safely and has shut down to prevent damage.

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (the flexible silver hose) underneath your boiler.
  2. Slowly open the one or two taps/levers on the hose until you hear water entering.
  3. Watch the pressure gauge and close the taps firmly once it reaches 1.5 bar.

Parts commonly replaced

  • Filling loop valve
  • Pressure sensor
  • Expansion vessel repressurisation

Related codes

Full explanation for Water Pressure 3/3
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